Biodiversity as insurance
Diversity buffers against functional changes
No one species fills all the roles of an ecosystem
Today’s topic: Species Diversity
- Intricate webs of interacting organisms
- 2,000,000 species are known
- ~18,000 new species discovered per year
- estimated 87% of Eukaryotas unknown
- Reflects billions of ways organisms have adapted, over and over, to a changing planet
- Humans relentlessly alter ecosystems
- aquatic and terrestrial
- ~150 species go extinct each day
Measuring biodiversity (e.g. Simpson’s or Shannons index)
Species types (native, endemic, non-native, exotic, invasive)
The march of the cane toad
Exotic vs Invasive
Species diversity declines from tropics
Species diversity declines at altitude
Mapping biodiversity: Soils
Mapping biodiversity: Oceans
Ecoregions: Where biodiversity hotspots exists
Hotspots: Andean uplift and bird diversity
Hotspots: Endemic species of Madagascar
Threats to biodiversity
Threats: Invasive species are increasing
- Change physical and biotic environment
- Aquatic ecosystems heavily affected
- Impacts outweigh natural extinction rates
Ecoregions versus humans
Homogenization: ecosystems losing their uniqueness
- Replacement of native species by exotics
- invasives are highly competitive
- Taxonomic homogenization
- increased similarity of species
- plants, insect, fish, birds & mammals
- Biotic homogenization tied to humans
- landscape simplification
- habitat loss
Homogenization: Megafauna
